Kristen Stewart cried while filming 'Eclipse'

Slade says that Stewart, who plays Bella Swan in the Twilight Saga, cried because she found it difficult to relate to her character, according to the Vancouver Sun.

"[Kristen] would say, 'I don't know who Bella is to me.' In a lot of ways, I think she felt Bella was the antithesis to her, which presented a lot of challenges for Kristen… She would beat herself up about it, because she wants to be there. She never wants to leave a scene undone," said Slade.

Slade admitted that all the actors experienced insecurities while shooting the film, but revealed that Stewart was the most sensitive.

"Kristen, in particular, was very tough on herself," Slade explained. "Even in rehearsals with Rob, there was a similar spiralling that would happen."